Marvel and DC Comics have made a combined 19 superhero movies since they started turning their respective comic characters into interconnected movie franchises in 2008. Of those 19, a woman has played the movie's top role in exactly zero.

That changes June 2, when DC/Warner Bros. releases “Wonder Woman,” with Gal Gadot playing the titular character.

The film, directed by Patty Jenkins — one of only three women to direct a live-action film with a budget of over $100 million — is another step forward for women in the superhero and science fiction sphere, coming on the heels of Katherine Waterston’s starring role in “Alien Covenant” and a pair of new Star Wars movies (“The Force Awakens” and “Rogue One”) that, respectively, featured Daisey Ridley and Felicity Jones playing the films’ main protagonists.

But while one is better than none, the fact remains that DC and Marvel made a combined 19 superhero movies with men in the lead before starring a woman. (Warner Bros.’ relatively new DC Extended Universe has made 4, whereas Marvel has made 15).

So will “Wonder Woman” be an irregularity, or is the film’s breakthrough the beginning of a new era of frequent female protagonists in a field of films that have thus far been male-dominated?

Martha Lauzen, executive director of the Center for the Study of Women in Television and Film at San Diego State University, leads a team that has been taking a truth lasso to the numbers since 1998. And while she has found Hollywood still functions far from parity, there are minor signs of improvement.

Overall, the Center for the Study of Women in Television and Film found that women made up 29 percent of all protagonists in the top 100 domestic grossing films in 2016, which was up 7 percent from the previous year and is a record. The study also found females accounted for 37 percent of main characters in films.

But even amid this improvement, women largely remain locked out of the top role in certain genres.

“Female protagonists were most likely to appear in comedies (28 percent), followed by dramas (24 percent), horror films (17 percent), animated features (14 percent), science fiction films (14 percent), and action films (3 percent),” Lauzen said.

Researchers have found a major problem with ‘The Little Mermaid’ and other Disney movies. (Daron Taylor/The Washington Post)

Lauzen also said high-profile female protagonists in films like “Alien Covenant” and “Wonder Woman” can create a misleading impression among viewers about the current state of female representation in the film industry.

“A few high-profile cases can dramatically skew our perceptions of how women are faring as protagonists or in important behind-the-scenes roles,” Lauzen said. “That's why it is so important to count the number of females on screen and behind the scenes. I would also note that 2016 was a very good year for female protagonists.”

It’s not as if this is the first time a female has led a major film. Who could forget Ripley in “Alien”? And even in the comic book superhero realm, Halle Berry  starred in the doomed “Catwoman” in 2004, while Jennifer Garner starred in "Elektra" in 2005. (Those films both came before the current expanded universe series that began with the 2008 release of Marvel's "Iron Man.")

But despite past high-profile roles for women, they have remained exceptions to the Hollywood norm -- especially in action movies.

As studios mull making more movies with female stars, they're likely to watch to see how “Wonder Woman” performs both critically and, most importantly, financially.

“Certainly, high-profile tentpole features with female protagonists that do well at the box office help build the case that these films can be as profitable as films featuring males, both domestically and internationally,” Lauzen said.

So far, things look good on the critical side. Bloggers and film critics have largely been raving about the film, with most praise going to Jenkins and Gadot — who briefly appeared in last year’s “Batman v Superman: Dawn of Justice.”

And while the coming superhero lineups remain dominated by men, more women will be getting roles soon.

Marvel plans to release eight films by 2019. Out of those films, two will feature a central female protagonist — Brie Larson in “Captain Marvel” and Evangeline Lily in “Ant-Man and the Wasp.” On the DC side, Warner Bros. has a few projects lined up, and in terms of female-led films, David Ayer is slated to direct “Gotham City Sirens” and Joss Whedon is currently attached to “Batgirl.”